The attainment of satisfactory, interference free results from wind tunnel tests at transonic speeds has been the objective of a number of experimental and theoretical investigations. Previous studies have shown that wind tunnels with perforated wall test sections are capable of providing interference free test conditions at Mach number 1.20. These studies concluded that perforated walls with the axes of the holes inclined 600 into the airstream and with an open-area ratio of 6 percent produced reasonably good test results for models having blockage ratios as large as 2 percent. However, wall interference effects in the Mach number range from 0.95 to 1.10 were not satisfactorily eliminated with this wall configuration. The present study was conducted in the 1-Foot Transonic Tunnel (lT) to experimentally investigate the feasibility of alleviating the wall interference effects in this Mach number range. Wall interference effects on the pressure distributions of several non-lifting bodies of revolution were obtained as a function of Mach number wall porosity, and wall angle. In addition, to establish a basis for comparison. lnterference free data were obtained from tests of 0.008-percent blockage models in the 16-Foot Transonic Circuit.